My project aims to contribute to a better understanding of constraints on adaptation. In response to an environmental change, populations can migrate to another place, be adapted through the mechanism of phenotypic plasticity, or evolve by natural selection (local adaptation). Our theoretical models fail to predict evolutionary change of populations. This suggests the presence of few constraints on adaptation. During my PHD project, I try to estimate and quantify some of constraints on adaptation, such as spatio-temporal patterns in selection regimes, by working on long term dataset (37 years) of Mediterranean blue tits.